Mustang-themed Double Bridge Hammock (Image heavy!)
First, a little bit of background. I joined HF a year or so ago, and immediately fell in love with the idea of a double bridge hammock. After searching the forums and reading for a while, though, I quickly realized that I'd need to try my hand at a standard bridge hammock before I even thought about doing a double.
Following the excellent writeups from Grizz and Teedee (along with all the other excellent information available), I came up with my first version of a single bridge hammock (threads are here and here.
Surprisingly, my first effort worked out OK. I spent some time fidgeting with the suspension and making an Insultex underquilt à la TeeDee's method; I haven't uploaded those pictures yet. Suffice to say the hammock is comfortable, and I learned a lot during the process of making it.
So now, full of (false?) confidence, I've decided to take a stab at making a double bridge hammock. I've taken the basic structure from studying dblhmmck's posts (specifically, the basic fabric pattern), and I've kind of been running from there. This thread will chronicle the progress/challenges, and hopefully lead to some good ideas from the more experienced DIY'ers out there. If you're curious about the color scheme -- my wife has a bright yellow mustang convertible, and I'm trying to mimic that to help increase her enthusiasm for the project :D
I decided to start with a bridge hammock sized to my wife and myself. I'm 5'4 and she's shorter, so I'm using a hammock length of 72" (4" allowance at top & bottom), a width of 44", and an arc cut depth of 6". I used a posterboard on which I traced and cut out a parabola 72" long and 6" high as my template for my arc cuts.
Here you can see both the cut edge of the fabric and the template.
So I cut out two matching hammocks (44" wide, 72" long with a 6" arc cut on each side. I followed the method of dblhmmck to create the overlap -- basically, you overlay the two hammocks so that you have a 50% overlap at the foot end and a 10% overlap at the head end, and trim off the excess fabric. You can see the results below. These images show a preliminary version of dblhmmck's design with the overlap stopping at the shoulder; I re-cut after I took these pictures to have the overlap be 10% at the head end.
Next, I looked at the edges. The head and foot end are finished with grosgrain ribbon. For the arc support, I'm using 1/2" polyester webbing, and I decided to join the two halves together using a 1" piece of polypro webbing. You can see the first piece finished below, as well as a closeup of the webbing loops on the arc and the center webbing.
The central 1" webbing piece I sewed on with a single line of stitches, then sewed the second piece on top of it, so that the webbing is "sandwiched" between the two halves of the hammock. I then rolled the seam once (so I have two layers of fabric above & below the polypro webbing, and sewed 5 lines of stitching (since I'm paranoid about it unrolling and dumping us out the bottom).
Finally, in order to give me two distinct hammocks (instead of one large bridge hammock where both occupants get smooshed together), I sewed a piece of 1/2" webbing down the middle. I have loops spaced every 8", as well as loops at the end - this will give me the ability to either use the webbing as the support for the center or to hang the center webbing from a rope arc. That's still more of an idea than anything well thought-out.
I have some images of my first test hang. I just wanted to see what it looked like hanging up, so these in no way represent the final version. I just took some mason line and some old dowels/broom handles and hung it up. I was thinking at first that it might be nice to use a single spreader bar at the top; the angled structure of the head end that I have now prevents this - I'm going to have to use two separate spreader bars at the end, meeting in the middle at the center webbing.
I've since acquired some spreader bars and put on a preliminary version of the rigging (I'm going to be going with a ridge "triangle" and a three-tree suspension system). Heading out tomorrow for the first "real" test hang and to try and get my suspension dialed in. Here's hoping :laugh:
First & Second Hang report
So I took it out last week, then again this weekend. Here's a couple of pictures, and the hang report.
I bought some Spyderline to do my temporary suspension, since I figured it was a good compromise between cheap and strong. I tied up all my suspension triangles with taut-line hitches (threaded through some webbing pockets (similar to TeeDee's) that I made out of 1 1/2" polypro webbing from Strapworks). I had a separate line for each attachment point; I joined each triangle together with a Zeppelin bend and larks-headed the result through the steel rings I was using.
At the head end, I have two separate suspension triangles, each one toggled around a steel ring. There is a rope connecting the two steel rings; this is to prevent the triangles from getting pulled out of shape if the trees aren't precisely in the right positions. At the foot end, there is just one suspension triangle, with an amsteel whoopie looped around the steel ring and attached with a fixed eye to the support webbing in the center of the hammock.
The three steel rings I used (two at the head end, one at the foot end) were attached to 3 6' whoopie slings that were attached to toggled tree straps. I plan to upgrade those to dutch buckles when time & money permit.
All well and good, right? Well, unfortunately, it seems that I underdesigned a few things. When I got in by myself, it held me just fine. However, when my lovely (and much lighter than me) wife joined me, there were a few critical failures. Thankfully, nothing structural in the hammock. I was initially using some carbon fiber toggles that I made from an old arrow a friend gave me. Word of advice - carbon fiber arrows don't do well being used as toggles.
After the second one failed on me, I gave up with them and went and found some big 1" diameter sticks to use. The second failure I had came from the Spyderline; the line connecting the two head rings snapped on me. Altogether, I only got dropped three times, none from very high up. Still, not fun, and it sent me to the store for some better rope (amsteel) and a needle to start splicing.
After a few busy days of splicing, I got all my slings made. Currently, the hammock has short whoopies for all the suspension triangle ropes (6) and ridgelines (3), as well as for the three attachment points to the tree straps. I also upgraded my steel rings to more robust rappel rings from REI - better safe than sorry, and I don't think I should even bother trying to make the first one ultralight :D. I also upgraded the rope on the foot end of the hammock to 1/4" amsteel - probably overkill, but I'd rather not get us dropped and convince my wife that hammocking is suicidal. :)
This weekend I took it out for a second test; you can see below that it holds me and a friend, as well as me and my wife together.
No breaking or ominous creaking; the amsteel (unsurprisingly) seems quite a bit more robust than the first suspension. One thing that I wasn't expecting; the two ridgelines running parallel to the two hammock bodies didn't perform at all as expected. Basically, when one person is in the hammock, the opposite ridgeline gets taut, and the hammock hangs *very* diagonally. You can see in the pictures that I replaced the two red ridgelines with a test version - just a white polypro rope that I had on hand. It's hanging loosely; getting the ridgeline working is the last thing that I think I'll need to do. After that it'll just be tweaking suspension triangle lengths, then making some endcaps and adding a bugnet, then actually (gasp!) trying it out :)
What do you think?